"The primary symptoms are nausea and vomiting, and then followed shortly thereafter with diarrhea, some low-grade fevers, headaches, body aches, backaches," said Dr. Greg Bonacquisti, the hospital's medical director

Doctors said It's no surprise that so many are infected, because the bug is highly contagious.

"These kids will pick it up just by coughing, respiratorily spread -- touching things, grabbing a doorknob," Bonacquisti said.

Crews worked late into the night to sanitize the school, hoping to stop the spread of the virus.

"We're also doing heavy cleaning in areas where we've seen concentrations of the illness -- in our athletic departments, our cheer and drill areas, as well as our other classrooms," Fowler said.

The district will monitor all of its schools. Closing schools for disinfection is an option if the virus seems to be spreading at a higher rate. But for now, the district is asking parents with sick children to keep them at home.